Used birch plywood to create frames
Stains went on well
Created wipe on poly from minwax satin polyurethane mixed with mineral spirits at 75/25 ratio.
Wiped on first coat then waited approx 5 hours and applied 2nd coat. Turned out great so far but had to stop for 24 hours or so.
Sanded a couple frames very lightly with 320. Seemed to make scratches and dull color despite very light sanding so stopped after a few frames and added another layer of poly to just those. The sanding did not remove color completely but appeared dulled even after wiping with mineral spirits and letting that dry)
The frames sanded are smoother in appearance and can only see scratch marks if at an angle but the frames without sanding do not have the scratches so I prefer to not touch them. However, I worry about the wood decaying over time as have read occurs if wood is not finished.
I am unsure if there is enough finish on the non-sanded frames and don't want to cause same problems as the sanded frames so do not believe sanding and applying poly is the way to go but believe I waited too long at this point to apply more layers of poly if I don't sand.
Any insight would be much appreciated on what I should do or if I should do nothing and not worry there may not be enough finish on the frames.